Pre-fabricated metal enclosures used, for example, at electrical sub-stations are typically unloaded from a semi-trailer using a large mobile crane system. The crane normally attaches to the base of the pre-fabricated enclosure, lifts the pre-fabricated enclosure from the trailer bed, and relocates the enclosure onto a pre-laid foundation. The crane system is sometimes not practical for transferring the pre-fabricated enclosure at a job site due to high voltage overhead power lines, trees, strong winds, or other environmental factors, conditions, or interferences. Additionally, the pre-laid foundation is intended to be level before the pre-fabricated enclosure is placed on it. However, any wobbling or swinging of the pre-fabricated enclosure as it is lowered by the crane makes it difficult to make adjustments to correct for any out-of-level conditions.
Recently, a “slide and lower” modular enclosure system comprising a sliding beam system and a system of coordinated self-contained hydraulic jack units was developed to pull a pre-fabricated metal enclosure off a semi-trailer using winches and slide beams, using a system of coordinated self-contained hydraulic jack units lowers the pre-fabricated enclosure to a pre-laid foundation. A patent application directed to that system was filed by the assignee of the present disclosure. However, the “slide and lower” modular enclosure system does not provide a way to rotate a building using that sliding beam system. Additionally, the “slide and lower” modular enclosure system requires the slide beams to be lifted to exactly the same height as the trailer, which is difficult when the trailer is not level.